Exporting to OBJ with textures not working properly
You are using Cycles materials, the exporter doesn't support exporting textures from node based materials.
Since Cycles is acting as the active Render engine the materials you created are for the Cycles renderer, and hence use node based definition. The obj exporter can't read these materials nor find textures used in them if any.
Set Blender Internal as Active render engine, redefine your materials, and reuse desired textures.
Also see .fbx export why there are no materials or textures?